The prevalence of thiamine or vitamin B1 deficiency has been documented in 21-98% of patients with heart failure. Thiamine has multiple effects on the cardiovascular system. It has important hemodynamic effects on the circulatory system as well as direct positive pharmacologic effects on the heart. Thiamine deficiency has been shown to cause cardiac hypertrophy, depressed cardiac contractility, and dysrhythmias. Thiamine is of particular interest in the management of heart failure for several reasons. Heart failure is a disease of the elderly whose micronutrient status is in need of attention. Heart failure patients tend to have inadequate nutrient intake, which has been associated with thiamine deficiency. Use of loop diuretic is associated with the loss of water-soluble vitamins, including thiamine. Several studies have examined the role of thiamine supplementation in patients with heart failure. Clinical trials in patients with congestive heart failure have shown that thiamine supplementation increases the systolic, diastolic, and central venous pressures, with a decline in heart rate and increase in left ventricular ejection fraction (LVEF). Thiamine acts as a vasodilator and reduces the afterload on the heart, thus improving cardiac function. Thiamine has also been reported to increase diuresis and natriuresis in patients with heart failure receiving diuretics.